This research has the following goals: 1. Correlation of Body Surface Potential Maps (based on potentials recorded from 180 electrode sites) with cardiac physiology and pathology in pediatric patients utilizing non-ECG diagnostic data derived from catheterization and echocardiographic measurements, as well as standard ECG and VCG recordings. 2. Studies and development of new methods for improved display and recording (storage) of maps for pattern recognition and classification. 3. Normalization of maps to eliminate the effect of body shape and surface inhomogeneities and to enhance spatial contrast by inward transformations(e.g., to the epicardium). 4. Improve applications of technology to simplify application of electrodes to the body and the electronics necessary to produce quality (low-noise) maps.